1. Field of the Invention
The present invention relates to an apparatus and a method for controlling optical device in which light emitted from an input optical waveguide is reflected by an inclinable reflecting surface so as to be made incident on an output optical waveguide.
2. Related Background of the Invention
Known as an example of optical device including a mirror having an inclinable reflecting surface is one disclosed in Patent Document 1 (U.S. Patent Application Laid-Open No. 2002/0076136). This optical device is an optical switch including a plurality of input ports and a plurality of output ports, and can optically couple any input port selected from the plurality of input ports to any output port selected from the plurality of output ports. Here, the input and output ports to be optically coupled to each other are selected by adjusting the inclination of the reflecting surface of the mirror. Such a mirror having an inclinable reflecting surface is made by MEMS (microelectromechanical systems) technology, for example. In such a MEMS mirror, the inclination of the reflecting surface is set according to the applied voltage value.
In order for such an optical device to carry out its operations at a high accuracy, it is important that the inclination of the reflecting surface of the mirror be controlled with a high accuracy. Therefore, in the optical device disclosed in the above-mentioned Patent Document 1, an optical multiplexer and an optical demultiplexer are disposed in an optical path from the plurality of input ports to the plurality of output ports. The optical multiplexer inserts pilot light into the optical path. The pilot light is reflected by the mirror, and is taken out from the optical demultiplexer. Thus taken pilot light is detected by a sensor, so that the state of inclination of the reflecting surface of the mirror is detected, whereby its inclination is controlled.